6株拮抗细菌对致病疫霉抑制作用的比较

Inhibition comparison of six antagonistic bacteria against Phytophthora infestans

比较在前期获得的明显抑制致病疫霉菌丝生长的6株细菌的抑菌性能及其防病潜力,为开发生防制剂防治马铃薯晚疫病提供依据.采用对峙培养法和打孔法测定6株细菌活体、菌液和无菌体发酵液对病菌菌丝生长的抑制作用,利用块茎切片法评价拮抗菌菌液对晚疫病的离体防治效果.结果表明,6株菌的菌液对菌丝生长的抑制作用均明显优于活体和无菌体发酵液,抑菌带宽度均在27mm以上,且均可引起菌丝体畸变,其中以WL2菌株的抑菌作用最强,活体、菌液和发酵液的抑菌带宽均在26mm以上,致畸作用也最强;此外,6株菌的菌液在离体块茎切片上的防病效果也以WL2菌液处理最好,病情指数最低(13.7),相对保护率最高(80.5%).这表明菌株WL2比其他5个菌株在防治马铃薯晚疫病方面有更大应用潜力.

The six bacterial strains including WL1, WL2, WR1, WR2, WK1 and M15, obtained in previously experiments, had the obvious inhibition to Phytophthora infestans mycelia growth.In order to clarify the biocontrol potential,the inhibition property and the disease prevention effects on in vitro tissue of six strains were compared in this experiment.The dual-culture method and punch method were adopted to determine the inhibition of living bacteria, bacterial liquid, as well as fermented liquid on P.infestans mycelia growth.The potato tuber slices method was used to evaluate the disease prevention effect of bacterial liquid.The results showed that the inhibition effects of six bacterial liquid to P.infestans growth were significantly greater than that of living bacteria and fermented liquid, and the inhibitory zones were above 27 ram, and all of them caused mycelial malformation.In which,bacterial liquid of WL2 strain displayed the strongest inhibitory effect, the inhibitory zones were above 26 mm,and caused the most serious malformation.In addition,WL2 bacterial liquid acquired the best disease prevention on in vitro tissue in comparison with other 5 strains,the disease index was only 13.7 ,and the relative protection ratio was up to 80.5 %.These results indicate that WL2 strain has more potential in control potato late blight in the future.